What were the main goals in using Crabster during the search and salvage operation? What was Crabster's main role in helping assess the ferry's condition or helping to search for people inside?

The Sewol sank at 45m water depth and the water was very turbid. It was dangerous for human divers to search the seafloor. I thought we could inspect the hull of sunken ferry and debris around her using Crabster’s acoustic instrument. And the information would be helpful for the planning of rescue and searching activity. When we reached the ferry site with Crabster system, the divers were going into the sunken ferry continuously for rescue. The highest priority was on the rescue activity by divers and all other team was restricted to approach to the rescue barge. Since Crabster is not able to go into sunken ferry, we also had to wait for approaching permission keeping apart from the rescue barge.